In the face of a growing demand for resources combined with an increasingly limited amount of space, greater amounts of food are being farmed and extracted from aquatic systems around the world.
Aquaculture Net. Image Credit: Adnan Buyuk/Shutterstock.com
Turning to the sea
With the advent of global climate change as well as rapidly changing socioeconomic dynamics, aquaculture represents a promising potential to improve food security. Aquaculture has a longstanding history and can be defined as the farming of aquatic organisms, which implies that animals and plants are managed and cultivated in marine or freshwater systems.
Most aquacultural systems rely on the breeding, rearing, and harvesting of fish, shellfish, algae, and other organisms in water environments. Therefore, aquaculture involves systems ranging from the exploitation of ocean-going pelagic fishes to the farming of inland shrimp fisheries.
In 2018, aquaculture supplied more than half of the world’s fish for human consumption as well as 32 million tonnes of aquatic algae and 26 000 tonnes of ornamental seashells. Finfish were the most farmed organism (54.3 million tonnes, USD 139.7 billion) followed by bivalve molluscs, which include mussels and oysters (17.7 million tonnes combined, USD 34.6 billion).
Aquaculture in the modern world
Developing aquacultural systems represents a promising candidate for improving and maintaining adequate food security. This is particularly thanks to the diversity of organisms and habitats, the abundance of exploitable organisms, and the rapid turnover of aquatic organisms, all of which provide considerable resource potential for human exploitation.
In a study, the global potential for fish and bivalve aquaculture was mapped in a study published in Nature Ecology and Evolution from 2017. The research team collected data to compare environmental productivity relative to the suitable environmental conditions for exploited organisms. The resulting models demonstrated that a considerable area is suitable for expanding marine aquaculture, and production may increase considerably.
If all suitable areas of finfish were developed, over 100 times the current consumption could be produced to accommodate any future requirements. Moreover, the major finding of this study was that if only the most productive areas of the ocean were developed for fish aquaculture, the amount of seafood that is currently captured by all wild fisheries could be grown using less than 0.015% of the ocean’s surface area. Such promising results provide key insight into alternative methods to feed the growing world population and relieving the pressure by wild fisheries.
Nonetheless, restructuring contemporary aquacultural systems may resolve only a few of the underlying issues generated by farming aquatic organisms. For instance, the decrease in organism fitness due to inbreeding, artificial selection, and environmental stress, poses a considerable threat to future fisheries.
In response, the use of gene-editing tools has been increasingly popular. Research from 2017, in particular, highlighted the use of single‐nucleotide polymorphism (SNP) and direct genotyping by sequencing (GBS) techniques to promote new developments in genetic diversity and breeding to date. For instance, genomic selection for traits of interest to aquacultures like growth, sex determination or disease resistance are increasingly common.
This study also discussed the potential for other tools including the use of bioinformatics for fisheries. The rapid progress of computational processing and the increased complexity that models can handle has made bioinformatics a tool with widespread applications for fisheries. In particular, understanding changes in growth and survival as well as establishing long term projections under future climate change, are only some of the insights that bioinformatics can provide.
Limitations to aquacultural practices
However, the dependency on aquatic-based food systems generates many consequences. Detrimental effects include extensive habitat degradation and destruction, the use of harmful chemicals and veterinary drugs to promote organism growth and eliminate unwanted species, the impact on wild stocks from organisms that have escaped farming conditions, and the inefficient or unsustainable production of fisheries-related products as well as the social and cultural impacts on aquaculture workers and communities.
Such consequences have widespread repercussions on stakeholders, consumers, surrounding populations, and the environment on a short- and long-term scale. Indeed, immediate and direct effects are readily observed but longer-term and indirect impacts on organism fitness, ecosystem resiliency, and the socioeconomic disparity is more complex and rarely considered.
The aforementioned study that mapped the global potential of aquaculture concluded that the socioeconomic status as countries represented the major limitations to fully developing aquacultural systems, which confounds the findings of the models. Indeed, social and economic instability negatively affects the capacity to establish and maintain productive and sustainable fisheries. To further exacerbate such instability, the fisheries of countries experiencing instability are often exploited by other countries and have limited support, ultimately restricting their competitivity.
Outlook and conclusion
Looking towards the future, the immediate challenge for aquaculture is the overexploitation of wild stocks while the advent of global climate change also represents a more long-term and sustained threat for many species. Of particular interest is the projected effects of ocean warming and acidification which are expected to induce range shifts and reduce physiological performance across many taxonomic groups.
The threat of overexploitation and climate change are gaining increasing awareness in fisheries management, yet solutions are also being developed to alleviate some of the short-term pressure from ecological and economic impacts.
For instance, improving the sustainability of current practices such as the development of aquafeed may be particularly useful. This was considered in a study from 2019 by Dawood and Koshio, who reviewed the use of sustainable fertilizer techniques through the use of microorganisms in fermentation to enhance the efficiency of the aquafeed industry. Such novel perspectives may be particularly insightful to use in combination with other techniques to address some of the consequences of aquaculture.
Indeed, such solutions may be used in conjunction with the use of novel designs in aquacultural systems that are also being implemented. These solutions include the use of large offshore fish farms, as well as the implementation of habitat-forming species surrounding fish farms to promote local biodiversity.
Ultimately, the socioeconomic constraints of aquaculture may limit the implementation of more effective and ecologically favorable strategies. However, the inclusion of scientific findings may refine the production potential and improve the outlook of aquacultural systems particularly in the face of global climate change.
References
- Aquaculture topics and activities. Aquaculture. In: FAO Fisheries Division [online]. Rome. Updated 21 October 2020. [Cited 11 December 2020].
- Dawood, M. A. O., & Koshio, S. (2019). Application of fermentation strategy in aquafeed for sustainable aquaculture. Reviews in Aquaculture, 12(2), 987–1002. https://onlinelibrary.wiley.com/doi/10.1111/raq.12368
- Gentry, R. R., Froehlich, H. E., Grimm, D., Kareiva, P., Parke, M., Rust, M., Gaines, S. D., & Halpern, B. S. (2017). Mapping the global potential for marine aquaculture. Nature Ecology & Evolution, 1(9), 1317–1324. https://doi.org/10.1038/s41559-017-0257-9
- Robledo, D., Palaiokostas, C., Bargelloni, L., Martínez, P., & Houston, R. (2017). Applications of genotyping by sequencing in aquaculture breeding and genetics. Reviews in Aquaculture, 10(3), 670–682. https://onlinelibrary.wiley.com/doi/10.1111/raq.12193
Further Reading